The present invention relates to a thermal insulating layer for body-like components, such as for instance machines, apparatuses, containers, equipment, gas and steam turbines and the like, including a plurality of planarly shaped elements or mats or pads, respectively located in an adjoining manner at the outside of the component.
The invention encompasses specifically thermal insulations for thermal machines, such as for instance gas turbines and steam turbines, which in case of inspection or revision of such machines must be easily removable and remountable. The object of the insulation of thermal machines is to reduce heat losses due to radiation and convection from the hot machine parts and to simultaneously ensure protection against contact. Decisive for the quality of an insulation in the field of thermal machines is a high heat resistivity, especially a value of heat resistivity over the entire surface to be insulated which is as constant as possible. Varying heat resistivities along the body of the machine lead positively to differing temperature distributions. These cause thermal stress or thermal deformations of the body of the machine which specifically in case of rotating thermal machines having small dimensional tolerances, can lead to considerable damage or even total destruction.
A special consideration for bodies of thermal machines consists in the complicated, spatial geometry of the surface. The turbines are for instance moulded bodies having surfaces which are spatially curved in various planes and with varying radii. This is augmented by numerous stubs and discharges which penetrate the curved surface. Every thermal machine needs periodic revisions or inspections for which the casing is opened whereby, the thermal insulation must be at least partially removed and remounted.
The known insulating systems feature various drawbacks. A procedure used specifically in early thermal machines is the hard coating. An insulating mass or fibrous material, respectively having a binding agent is sprayed on or applied by spatulas in a flowable state and forms after the setting a hard, concrete-like layer. This procedure has proven itself mainly in view of the complicated geometry of the surfaces and provided a jointless insulating layer having a constant heat resistivity. A drawback was, however, the high expenditure for maintenance operations. The insulating layer had to be destroyed at least in part and produced anew. Apart from the high work expenditure, the dust development was undesired too.
Another known procedure for insulating bodies of thermal machines uses a flexible insulation which can be removed and also remounted and which in accordance with the generally used insulating pads is soft. In order to achieve an approximate seamless structure the insulating pads are mounted in a staggered arrangement in two layers. Within a respective insulation layer the individual insulating pads can be mounted overlapped in order to still better stop heat losses due to convection through gaps. In this case the thickness of the insulation must be altogether constant in the area of the overlapping of two adjacent pads in order to not to locally increase the heat resistivity. This is made in this procedure by a wedge shaped, complimentary reduction of the thickness of the insulation at the area of the overlap. The drawback of this procedure is the high expenditure for the production at which the complicated geometry must be taken into consideration at the inner and the outer layer, as well. The parts of the inner and the outer layer are generally not in registry because the radii of curvature of the outer layer are increased by the thickness of the insulation of the inner layer. The two layers lead to a larger number of individual pads. Apart from the expenditure for mounting and dismounting, the danger of a mixing-up is especially feared. Mixed-up insulating pads can lead to clearances and gaps in the insulating system and thus to serious consequential thermal stresses and deformations in the body of the machine.
The object of the present invention is, therefore, the provision of a flexible insulation for thermal machines which can be demounted and also be mounted again and which is soft according to the principle of commonly applied insulating pads in order to render itself adjustable to the geometrically complicated surface to be insulated. It shall specifically reduce the number of the individual parts and ensure inspite thereof a substantially gap-less and practically constant heat resistivity over the entire surface.